Design, Manufacturing And Signal Conditioning Of An Integrated Micro Flow Sensor Based On Calorimetric Theory

Flow measurement is an important way for people to understand and control fluids, which plays a significant role in industrial production and process control. As microelectronics and MEMS technology matures, along with the rapid development of applications in micro total analysis system of various fields including medicine, manufacturing, analytical instrumentation and molecular biology and so on, the demand for fluid flow measurement and control has been increasing. Micro flow sensor fabricated with MEMS technology has advantage characteristics: low power consumption, low cost , simple structure, high sensitivity, thus it gains broad attention.This paper did some research on the design, fabrication and packaging of micro flow sensor based on Calorimetric theory, specifically including:1. With COMSOL Multiphysics, we did simulation of micro flow sensor based on Calorimetric theory including the coupling of electric and thermal field to understand the heat distribution of the resistance under the electric excitation, the coupling of flow and thermal filed to understand the influence of flow velocity on the heat distribution, the coupling of electric, thermal and flow flied to understand micro flow senor's key factors'influence and resistances'insulation layers'influence on its sensitivity.2. Based on glass and polyimide substrate, we implemented lift off technology to fabricate electrodes of micro flow sensor. Then based on silicon substrate, we implemented ion beam milling technology to manufacture electrodes of micro flow sensor. We, afterwards, designed different ways of packaging for those micro flow sensor electrodes.3. Having implementing the ion beam milling technology to form Au electrodes, we fabricated a micro flow sensor which was integrated inside the flow channel. It was realized by using SU-8 as the flow channel which integrated electrodes inside and packaged through the bonding between SU-8 and PDMS.4. Then we designed signal conditioning circuit for fabricated silicon based micro flow sensor and did initial testing of micro flow sensors (with SU-8 insulation layer and without it) using Whitestone Bridge to obtain the Voltage-Flow signal.With the development of microfluidic system, it is more and more demanding to integrate micro flow sensor for relatively lower flow rate measurement. The research results of this paper on micro flow sensor laid a foundation for further study and development.